In general, an apparatus for water treatment using capacitive deionization (CDI) may include a deionization filter including electrodes having nano-scale air gaps, and when a voltage is applied to the electrodes, the electrodes are polarized to allow ionic compounds in a medium to be adsorbed onto surfaces thereof to thereby be removed. With a medium containing dissolved ions flowing between two electrodes, a positive electrode and a negative electrode of the deionization filter, when DC power having a low potential difference is applied thereto, anion components of the dissolved ions may be adsorbed on the positive electrode and cation components thereof may be adsorbed on the negative electrode and concentrated thereon, respectively. Thereafter, when a current flows in a reverse direction to short-circuit the two electrodes, the concentrated ions may be desorbed from the respective electrodes. The apparatus for water treatment using capacitive deionization has advantages in that high energy efficiency is obtained because a high potential difference is not used, hazardous ions can be removed together with hardness components in the case of ion adsorption, and chemicals are not required in regeneration of the electrodes. However, in the related art apparatus for water treatment using capacitive deionization, since the saturated electrodes are regenerated through a regeneration process after the deionization process is finished, continuous deionization is not possible.